title: Smoking-related emphysema is associated with idiopathic pulmonary fibrosis and rheumatoid lung.
abstract: OBJECTIVE
  A combined pulmonary fibrosis/emphysema syndrome has been proposed, but the basis for this syndrome is currently uncertain. The aim was to evaluate the prevalence of emphysema in idiopathic pulmonary fibrosis (IPF) and rheumatoid lung (rheumatoid arthritis-interstitial lung disease (RA-ILD)), and to compare the morphological features of lung fibrosis between smokers and non-smokers.
  
  
  METHODS
  Using high-resolution computed tomography, the prevalence of emphysema and the pack-year smoking histories associated with emphysema were compared between current/ex-smokers with IPF (n = 186) or RA-ILD (n = 46), and non-chronic obstructive pulmonary disease (COPD) controls (n = 103) and COPD controls (n = 34). The coarseness of fibrosis was compared between smokers and non-smokers.
  
  
  RESULTS
  Emphysema, present in 66/186 (35%) patients with IPF and 22/46 (48%) smokers with RA-ILD, was associated with lower pack-year smoking histories than in control groups (P < 0.05 for all comparisons). The presence of emphysema in IPF was positively linked to the pack-year smoking history (odds ratio 1.04, 95% confidence interval (CI) 1.02-1.06, P < 0.0005). In IPF, fibrosis was coarser in smokers than in non-smokers on univariate and multivariate analysis (P < 0.01 for all comparisons). In RA-ILD, fibrosis was coarser in patients with emphysema but did not differ significantly between smokers and non-smokers.
  
  
  CONCLUSIONS
  In IPF and RA-ILD, a high prevalence of concurrent emphysema, in association with low pack-year smoking histories, and an association between coarser pulmonary fibrosis and a history of smoking in IPF together provide support for possible pathogenetic linkage to smoking in both diseases.
authors.affiliation: Interstitial Lung Disease Unit, Royal Brompton Hospital, London, UK.
authors.forename: Katerina M
authors.initials: KM
authors.lastname: Antoniou
authors.forename: Simon L
authors.initials: SL
authors.lastname: Walsh
authors.forename: David M
authors.initials: DM
authors.lastname: Hansell
authors.forename: Michael R
authors.initials: MR
authors.lastname: Rubens
authors.forename: Katharina
authors.initials: K
authors.lastname: Marten
authors.forename: Rachel
authors.initials: R
authors.lastname: Tennant
authors.forename: Trevor
authors.initials: T
authors.lastname: Hansel
authors.forename: Sujal R
authors.initials: SR
authors.lastname: Desai
authors.forename: Nikolaos M
authors.initials: NM
authors.lastname: Siafakas
authors.forename: Roland M
authors.initials: RM
authors.lastname: du Bois
authors.forename: Athol U
authors.initials: AU
authors.lastname: Wells
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000453:epidemiology* / Q000473:pathology; D016022:Case-Control Studies; D015331:Cohort Studies; D015897:Comorbidity; D004646:Emphysema / Q000453:epidemiology* / Q000209:etiology* / Q000473:pathology; D005260:Female; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000453:epidemiology* / Q000473:pathology; D016015:Logistic Models; D008168:Lung / Q000473:pathology; D017563:Lung Diseases, Interstitial / Q000453:epidemiology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D029424:Pulmonary Disease, Chronic Obstructive / Q000473:pathology; D012907:Smoking / Q000009:adverse effects*
keywords: emphysema; idiopathic pulmonary fibrosis; pathogenesis; rheumatoid lung; smoking